Biofilters for urban runoff pollutants

Abstract

Biofilms were produced on three media with different physical and chemical characteristics to determine how media characteristics and the microbial community influence the properties of the biofilm and its effect on remediating runoff pollutants. Water, sediment and rocks from an urban stream were used as the inoculum to provide a source of microbes acclimated to runoff pollutants. The chemical make-up of the extracellular polymeric substances (BPS) produced by the microbial community affects electrostatic and hydrophobic interactions with the substrata as well as molecules in the surrounding environment Thus the biofilm proteins and carbohydrates that make up the EPS and their hydrophobicities were assayed to determine their potential affects on remediating runoff pollutants. Based on these studies it appears that the medium affects the type of community that is attracted. The presence of degraders in this community seems to be the determining factor in contaminant degradation. The microbial community affects the EPS that is produced and it appears that the presence of EPS or the media itself may also affect degradation rate. The rate of degradation may also be affected by other factors such as diffusion of contaminant through the EPS, abiotic reactions or physiological state of the microbes. Further studies are needed to investigate these factors.